#include <iostream>
#include <fstream>
#include <sstream>
#include <iomanip>
#include <vector>
#include <string>
#include <utility>
#include <algorithm>
#include <optional>
#include <string_view>
#include <cstdint>
#include <cstring>
#include <cstdlib>
#include <cctype>
#include <cassert>
#include <errno.h>
#include <unistd.h>
#include <signal.h>
#include <sys/stat.h>
#include <sys/time.h>
#include "scheduler.h"
#include "process.h"
#include "error.h"
#include "multilog.h"
#include "referee.h"

using namespace std;


const char *const matchcachedir = "comp_cache";
const char *const playerlogdir = "comp_playerlogs";
const char *const gamelogdir = "comp_gamelogs";


static char hexchar(int n) {
	return "0123456789ABCDEF"[n];
}

static string makeSafe(const string_view str) {
	string res;
	res.reserve(str.size() + 3);

	for (char c : str) {
		if (isalnum(c)) {
			res += c;
		} else {
			res += '_';
			res += hexchar((c >> 4) & 0xf);
			res += hexchar(c & 0xf);
		}
	}

	return res;
}

// Only creates a single component
static void mkdirp(const string_view name) {
	if (mkdir(name.data(), 0755) < 0) {
		if (errno != EEXIST) {
			perror("mkdir");
			exit(1);
		}
	}
}

static int64_t fileLastModified(const string_view fname) {
	struct stat st;
	if (stat(fname.data(), &st) < 0) {
		if (errno == EEXIST) return 0;
		perror("stat");
		exit(1);
	}
#ifdef __APPLE__
	return st.st_mtimespec.tv_sec * 1000000LL + st.st_mtimespec.tv_nsec / 1000;
#else
	return st.st_mtim.tv_sec * 1000000LL + st.st_mtim.tv_nsec / 1000;
#endif
}

static int64_t gettimestamp() {
	struct timeval tv;
	gettimeofday(&tv, nullptr);
	return tv.tv_sec * 1000000LL + tv.tv_usec;
}

struct Player;

// Methods represent results for player 1, unless inverted
struct MatchResult {
	enum class Win {
		win, loss, tie, timeout, crash
	};

	enum class Status {  // crash is not used yet
		ok, timeout, crash
	};

	Status status;
	int sc1, sc2;
	size_t ms1 = 0, ms2 = 0;

	int score() const;
	Win getWin() const;
	string describe(const Player &p1, const Player &p2) const;
	MatchResult inverted() const;
};

struct Player {
	string fname, safename;
	vector<MatchResult> results;
	int64_t lastModified;

	Player(const string &fname)
			: fname(fname), safename(makeSafe(fname)),
			lastModified(fileLastModified(fname)) {}
};

int MatchResult::score() const {
	return sc1;
}

MatchResult::Win MatchResult::getWin() const {
	switch (status) {
		case Status::ok:
			if (sc1 > sc2) return Win::win;
			else if (sc1 == sc2) return Win::tie;
			else return Win::loss;

		case Status::timeout:
			return Win::timeout;

		case Status::crash:
			return Win::crash;

		default:
			assert(false);
	}
}

string MatchResult::describe(const Player &p1, const Player &p2) const {
	string prefix;
	switch (getWin()) {
		case Win::win: prefix = p1.fname + " won: "; break;
		case Win::loss: prefix = p2.fname + " won: "; break;
		case Win::tie: prefix = "tie: "; break;
		case Win::timeout: prefix = "timeout: "; break;
		case Win::crash: prefix = "crash: "; break;
	}
	return prefix + to_string(sc1) + "-" + to_string(sc2);
}

MatchResult MatchResult::inverted() const {
	MatchResult r;
	r.status = status;
	r.sc2 = sc1; r.sc1 = sc2;
	r.ms2 = ms1; r.ms1 = ms2;
	return r;
}

struct Params {
	bool referee_verbose = false;
	string refereePath;
	int num_matches = 5;
	size_t timeout_msec = 10000;
};

static string gameCodeName(const Player &p1, const Player &p2, int index) {
	return p1.safename + "-" + p2.safename + "-" + to_string(index);
}

static string playerLogPath(const Player &p1, const Player &p2, int index, int who) {
	return string(playerlogdir) + "/" + gameCodeName(p1, p2, index) + "-" + to_string(who) + ".txt";
}

static string matchCachePath(const Player &p1, const Player &p2, int index) {
	return string(matchcachedir) + "/" + gameCodeName(p1, p2, index) + ".txt";
}

static string gameLogPath(const Player &p1, const Player &p2, int index) {
	return string(gamelogdir) + "/" + gameCodeName(p1, p2, index) + ".txt";
}

static optional<MatchResult> readMatchCache(const Player &p1, const Player &p2, int index) {
	string path = matchCachePath(p1, p2, index);

	ifstream f(path);
	if (!f) return nullopt;

	int64_t cacheStamp = fileLastModified(path);
	if (p1.lastModified > cacheStamp || p2.lastModified > cacheStamp) {
		return nullopt;
	}

	MatchResult mres;
	string word;
	f >> word >> mres.sc1 >> mres.sc2 >> mres.ms1 >> mres.ms2;
	if (!f) {
		return nullopt;
	}

	if (word == "ok") mres.status = MatchResult::Status::ok;
	else if (word == "timeout") mres.status = MatchResult::Status::timeout;
	else if (word == "crash") mres.status = MatchResult::Status::crash;
	else return nullopt;

	return mres;
}

static void writeMatchCache(const Player &p1, const Player &p2, int index, const MatchResult &mres) {
	string path = matchCachePath(p1, p2, index);
	ofstream f(path);
	if (!f) {
		cout << endl << "ERROR: Cannot open match cache file '" << path << "'" << endl;
		throw StopCompetitionError();
	}

	switch (mres.status) {
		case MatchResult::Status::ok: f << "ok"; break;
		case MatchResult::Status::timeout: f << "timeout"; break;
		case MatchResult::Status::crash: f << "crash"; break;
	}

	f << ' ' << mres.sc1 << ' ' << mres.sc2;
	f << ' ' << mres.ms1 << ' ' << mres.ms2 << endl;
}

static void recordResult(Player &p1, Player &p2, const MatchResult &result) {
	p1.results.push_back(result);
	p2.results.push_back(result.inverted());
}

static void playMatch(MultiLog &multiLog, Player &p1, Player &p2, int index, const Params &params) {
	int logId = multiLog.add(p1.fname + " - " + p2.fname + ": ");

	if (optional<MatchResult> optres = readMatchCache(p1, p2, index)) {
		multiLog.append(logId, optres->describe(p1, p2) + " (cached)");
		multiLog.complete(logId);
		recordResult(p1, p2, *optres);
		return;
	}

	MatchResult mres;

	string gamelog_path = gameLogPath(p1, p2, index);
	ofstream gamelog(gamelog_path);
	if (!gamelog) {
		cout << "ERROR opening game log file " << gamelog_path << endl;
		throw StopCompetitionError();
	}

	Referee referee(params.referee_verbose, params.refereePath, {p1.fname, p2.fname});

	gamelog << "Player 1: " << p1.fname << "\n"
	        << "Player 2: " << p2.fname << "\n\n" << flush;

	Process procs[2] = {Process(p1.fname), Process(p2.fname)};
	procs[0].redirectStderr(playerLogPath(p1, p2, index, 1));
	procs[1].redirectStderr(playerLogPath(p1, p2, index, 2));
	procs[0].run();
	procs[1].run();

	while (true) {
		auto event = referee.nextEvent();

		if (auto readEvent = get_if<Referee::ReadEvent>(&event)) {
			Process &proc = procs[readEvent->player];

			proc.unStop();
			int64_t start = gettimestamp();

			optional<string> oline = proc.readLine();
			if (!oline) {
				cout << "ERROR reading move from player " << readEvent->player + 1
				     << " (game " << gameCodeName(p1, p2, index) << ")" << endl;
				cout << "(process exit code: " << proc.waitPoll() << ")" << endl;
				throw StopCompetitionError();
			}

			(readEvent->player == 0 ? mres.ms1 : mres.ms2) += gettimestamp() - start;
			proc.stop();

			readEvent->callback(*oline);

			if (mres.ms1 / 1000 > params.timeout_msec || mres.ms2 / 1000 > params.timeout_msec) {
				mres.status = MatchResult::Status::timeout;
				mres.sc1 = mres.sc2 = 0;
				referee.terminate();
				break;
			}

		} else if (auto writeEvent = get_if<Referee::WriteEvent>(&event)) {
			if (!procs[writeEvent->player].writeLine(writeEvent->line, writeEvent->allowBrokenPipe)) {
				cout << "ERROR writing move to player " << writeEvent->player + 1
					 << " (game " << gameCodeName(p1, p2, index) << ")" << endl;
				throw StopCompetitionError();
			}

		} else if (auto gamelogEvent = get_if<Referee::GamelogEvent>(&event)) {
			gamelog << "P" << gamelogEvent->player + 1 << ": "
			        << gamelogEvent->line << endl;

		} else if (auto endEvent = get_if<Referee::EndEvent>(&event)) {
			mres.status = MatchResult::Status::ok;

			assert(endEvent->scores.size() == 2);
			mres.sc1 = endEvent->scores[0];
			mres.sc2 = endEvent->scores[1];
			break;

		} else if (auto errorEvent = get_if<Referee::ErrorEvent>(&event)) {
			cout << "ERROR in player " << errorEvent->player + 1 << ": " << errorEvent->message
				 << " (game " << gameCodeName(p1, p2, index) << ")" << endl;
			gamelog << endl
			        << "ERROR in P" << errorEvent->player + 1 << ": " << errorEvent->message << endl;
			throw StopCompetitionError();

		} else {
			assert(false);
		}
	}

	for (int i = 0; i < 2; i++) {
		procs[i].unStop();
		if (procs[i].waitPoll() == -1) usleep(10000);
		int ret = procs[i].terminate();
		if (ret != 0 && ret != 1009) {
			cout << "Player " << i+1 << " exited with code " << ret << endl;
		}
	}

	multiLog.append(logId, mres.describe(p1, p2));
	multiLog.complete(logId);

	gamelog << "\nResult: " << mres.describe(p1, p2) << "\n"
	        << "P1 took " << mres.ms1 / 1000000.0 << " seconds\n"
	        << "P2 took " << mres.ms2 / 1000000.0 << " seconds\n" << flush;

	writeMatchCache(p1, p2, index, mres);
	recordResult(p1, p2, mres);
}

static void playerPit(Scheduler &scheduler, MultiLog &multiLog, Player &p1, Player &p2, const Params &params) {
	for (int i = 0; i < params.num_matches; i++) {
		scheduler.submit([i, &p1, &p2, &params, &multiLog]() {
			playMatch(multiLog, p1, p2, i + 1, params);
		});
	}
}

static void fullCompetition(Scheduler &scheduler, MultiLog &multiLog, vector<Player> &players, const Params &params) {
	for (size_t p1i = 0; p1i < players.size(); p1i++) {
		for (size_t p2i = p1i + 1; p2i < players.size(); p2i++) {
			playerPit(scheduler, multiLog, players[p1i], players[p2i], params);
			playerPit(scheduler, multiLog, players[p2i], players[p1i], params);
		}
	}
}

static void usage(const char *argv0) {
	cerr << "Usage: " << argv0 << " [OPTIONS] <referee> <players...>\n"
		"  --noansi   Don't use fancy back-updating log output\n"
		"  --vs       Verbose scheduler output (use with --noansi)\n"
		"  --vr       Verbose referee-handling output (use with --noansi)\n"
		"  -j <NUM>   Set number of parallel games (default ncores/2)\n"
		"  -n <NUM>   Set number of matches per player pairing (default "
			<< Params{}.num_matches << ")\n"
		"  -T <MSEC>  Set player timeout in milliseconds (default "
			<< Params{}.timeout_msec << ")\n";
}

int main(int argc, char **argv) {
	Params params;
	vector<Player> players;
	bool multilog_fancy = true;
	bool scheduler_verbose = false;
	int num_threads = std::thread::hardware_concurrency() / 2;

	for (int i = 1; i < argc; i++) {
		if (strcmp(argv[i], "-h") == 0 || strcmp(argv[i], "--help") == 0) {
			usage(argv[0]);
			return 0;
		} else if (strcmp(argv[i], "--noansi") == 0) {
			multilog_fancy = false;
		} else if (strcmp(argv[i], "--vs") == 0) {
			scheduler_verbose = true;
		} else if (strcmp(argv[i], "--vr") == 0) {
			params.referee_verbose = true;
		} else if (strcmp(argv[i], "-j") == 0 && i + 1 < argc) {
			char *endp;
			num_threads = strtol(argv[i+1], &endp, 10);
			if (!argv[i][0] || *endp || num_threads <= 0) {
				cerr << "Invalid number to -j" << endl;
				return 1;
			}
			i++;
		} else if (strcmp(argv[i], "-n") == 0 && i + 1 < argc) {
			char *endp;
			params.num_matches = strtol(argv[i+1], &endp, 10);
			if (!argv[i][0] || *endp || params.num_matches <= 0) {
				cerr << "Invalid number to -n" << endl;
				return 1;
			}
			i++;
		} else if (strcmp(argv[i], "-T") == 0 && i + 1 < argc) {
			char *endp;
			params.timeout_msec = strtoull(argv[i+1], &endp, 10);
			if (!argv[i][0] || *endp || params.timeout_msec <= 0) {
				cerr << "Invalid number to -T" << endl;
				return 1;
			}
			i++;
		} else if (argv[i][0] == '-') {
			cerr << "Unknown option/flag '" << argv[i] << "'" << endl;
			return 1;
		} else if (params.refereePath.empty()) {
			params.refereePath = argv[i];
		} else {
			players.emplace_back(argv[i]);
		}
	}

	if (players.empty()) {
		usage(argv[0]);
		return 1;
	}

	MultiLog multiLog{multilog_fancy};

	mkdirp(matchcachedir);
	mkdirp(playerlogdir);
	mkdirp(gamelogdir);

	signal(SIGPIPE, [](int){});

	Scheduler scheduler(scheduler_verbose, num_threads);
	fullCompetition(scheduler, multiLog, players, params);
	scheduler.finish();

	vector<pair<string, int>> scores;
	for (const Player &player : players) {
		int score = 0;
		for (const MatchResult &result : player.results) {
			score += result.score();
		}
		scores.emplace_back(player.fname, score);
	}

	sort(scores.begin(), scores.end(),
			[](const pair<string, int> &a, const pair<string, int> &b) { return a.second > b.second; });

	size_t maxlen = strlen("Player");
	for (const Player &player : players) {
		maxlen = max(maxlen, player.fname.size());
	}

	cout << endl << setw(maxlen) << "Player" << " | " << "Score" << endl;
	cout << string(maxlen, '-') << "-+------" << endl;

	for (const auto &p : scores) {
		cout << setw(maxlen) << p.first << " | " << p.second << endl;
	}
}